
function show(){
//  var msg = "zhangsan ";
    msg = "zhangsan";
}
show();
console.log(msg);
console.log(0.1+0.2);
console.log(Number.MAX_VALUE);
console.log(Number.MIN_VALUE);
console.log(Number.MAX_SAFE_INTEGER);
console.log(Number.MIN_SAFE_INTEGER);
var a = 10;
console.log(isFinite(a));
console.log(Number.POSITIVE_INFINITY);
console.log(Number.NEGATIVE_INFINITY);
console.log(3/0);
console.log(3/'a');
console.log(NaN==NaN);
console.log("==========================================");

console.log(isNaN("number"));
console.log(isNaN("10"));
console.log(isNaN(NaN));
console.log("==========================================");
var src = "zero \n network";
document.write(src);

console.log("==========================================");
var a = 10,b = 20;
console.log(a==b);
if(a==b){
    console.log("相等");
    
}else{
    console.log("不相等");
    
}

var shuqingle;
console.log(shuqingle);

var car=null;
console.log(car);
console.log(typeof car);
console.log("==========================================");
console.log(undefined == null);















